U.S. patent number 4,739,865 [Application Number 06/880,189] was granted by the patent office on 1988-04-26 for clutch/brake unit with self-contained actuating pump system.
This patent grant is currently assigned to Force Control Industries, Inc.. Invention is credited to Stephen L. Carmichael, Jerry L. Yater.
United States Patent |
4,739,865 |
Yater , et al. |
April 26, 1988 |
Clutch/brake unit with self-contained actuating pump system
Abstract
A housing encloses a supply of oil and has opposite end portions
supporting axially aligned input and output shafts. Interfitting
annular clutch plates and discs provide for connecting the input
shaft to the output shaft, and interfitting annular brake plates
and discs provide for braking the output shaft to the housing in
response to axial movement of a non-rotating oil actuated piston
supported within the housing concentrically with the output shaft.
Oil recirculating passages are provided within the housing for
cooling and lubricating the plates and discs, and a positive
displacement high pressure annular pump forms an extension of the
housing around the inlet shaft. The pump has inner and outer thin
flat rotors and pressurizes a portion of the oil within the housing
sufficiently to actuate the piston through the control of a
solenoid actuated valve unit mounted on the housing.
Inventors: |
Yater; Jerry L. (Hamilton,
OH), Carmichael; Stephen L. (Hamilton, OH) |
Assignee: |
Force Control Industries, Inc.
(Fairfield, OH)
|
Family
ID: |
25375683 |
Appl.
No.: |
06/880,189 |
Filed: |
June 30, 1986 |
Current U.S.
Class: |
192/18A;
192/113.34; 192/85.53; 418/181 |
Current CPC
Class: |
F16D
67/04 (20130101) |
Current International
Class: |
F16D
67/00 (20060101); F16D 67/04 (20060101); F16D
067/04 () |
Field of
Search: |
;192/18A,86,58C,12C,87.17,87.18,113B ;188/151R ;418/61B,64,181 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Bonck; Rodney H.
Attorney, Agent or Firm: Jacox & Meckstroth
Claims
The invention having thus been described, the following is
claimed:
1. Apparatus comprising a housing having means for containing a
supply of oil, an input shaft and an output shaft rotatably
supported within said housing on a common axis of rotation, a
series of interfitting clutch plates and clutch discs within said
housing, said clutch plates mounted on said input shaft for
rotation therewith and the interfitting said clutch discs mounted
on said output shaft for rotation therewith, a series of
interfitting brake plates and brake discs positioned in axially
spaced relation to said series of clutch plates and discs, said
brake discs mounted on said output shaft for rotation therewith and
the interfitting said brake plates being supported for non-rotation
by said housing, a double actuating annular piston supported within
said housing coaxial with said output shaft and for non-rotating
axial movement, said piston having an outwardly projecting annular
portion cooperating with said housing to define a brake pressure
chamber and a clutch pressure chamber on opposite sides of said
piston portion, means connected to said piston for applying an
axially compressive force to said series of clutch plates and discs
in response to movement of said piston in one axial direction to
couple said input shaft with said output shaft, means for applying
an axially compressive force to said series of brake plates and
discs in response to movement of said piston in the opposite axial
direction for braking said output shaft to said housing, means for
recirculating oil within said housing and between said plates and
discs, a high pressure hydraulic gear pump including a pump body
supported by said housing and enclosing a substantially flat inner
rotor secured to said input shaft no rotation therewith, and
surrounded by a generally flat outer rotor, said inner and outer
rotors connected by intermeshing teeth, said outer rotor having a
rotary axis eccentric to said axis of said shaft, said inner rotor
having at least one less tooth than said outer rotor, and annular
wear plate disposed between said housing and said pump body and
engaging said inner and outer rotors, means defining an arcuate oil
receiving chamber within said wear plate adjacent said teeth, means
defining an inlet passage for directing oil within said housing to
said pump, means defining an outlet passage for directing
pressurized oil from said pump to said brake pressure chamber and
said clutch pressure chamber, electrically actuated valve means
connected to control selectively the flow of oil through said
outlet passage to either said brake pressure chamber or said clutch
pressure chamber, and separate adjustable pressure relief valves
connected to provide for independently adjusting the hydraulic
pressure to either said brake pressure chamber or said clutch
pressure chamber for conveniently selecting the torque transmitted
through either said brake plates and discs or said clutch plates
and discs.
2. Apparatus comprising a housing having means for containing a
supply of oil, an input shaft and an output shaft rotatably
supported within said housing on a common axis of rotation, a
series of interfitting clutch plates and clutch discs within said
housing, said clutch plates mounted on said input shaft for
rotation therewith and the interfitting said clutch discs mounted
on said output shaft for rotation therewith, a series of
interfitting brake plates and brake discs positioned in axially
spaced relation to said series of clutch plates and discs, said
brake discs mounted on said output shaft for rotation therewith and
the interfitting said brake plates being supported for non-rotation
by said housing, a double actuating annular piston supported within
said housing coaxial with said output shaft and for non-rotating
axial movement, said piston having an outwardly projecting annular
portion cooperating with said housing to define a brake pressure
chamber and a clutch pressure chamber on opposite sides of said
piston portion, means connected to said piston for applying an
axially compressive force to said series of clutch plates and discs
in response to movement of said piston in one axial direction to
couple said input shaft with said output shaft, means for applying
an axially compressive force to said series of brake plates and
discs in response to movement of said piston in the opposite axial
direction for braking said output shaft to said housing, means for
recirculating oil within said housing and between said plates and
discs, a high pressure hydraulic gear pump including a pump body
removably attached to said housing and including a rotor secured to
said input shaft for rotation therewith, means defining an inlet
passage within the lower portions of said housing and said pump
body for directing oil within said housing to said pump, an oil
filter within said inlet passage, means on said pump body for
removing said oil filter, means defining an outlet passage for
directing pressurized oil from said pump to said brake pressure
chamber and said clutch pressure chamber, electrically actuated
valve means connected to control selectively the flow of oil
through said outlet passage to either said brake pressure chamber
or said clutch pressure chamber, and separate adjustable pressure
relief valves connected to provide for independently adjusting the
hydraulic pressure to either said brake pressure chamber or said
clutch pressure chamber for conveniently selecting the torque
transmitted through either said brake plates and discs or said
clutch plates and discs.
3. Apparatus comprising a housing having means for containing a
supply of oil, an input shaft and an output shaft rotatably
supported within said housing on a common axis of rotation, a
series of interfitting clutch plates and clutch discs within said
housing, said clutch plates mounted on said input shaft for
rotation therewith and the interfitting said clutch discs mounted
on said output shaft for rotation therewith, an annular piston
supported within said housing coaxial with said output shaft and
for non-rotating axial movement, said piston having an outwardly
projecting annular portion cooperating with said housing to define
a clutch pressure chamber, means connected to said piston for
applying an axially compressive force to said series of clutch
plates and discs in response to movement of said piston in one
axial direction to couple said input shaft with said output shaft,
means for recirculating oil within said housing and between said
plates and discs, a high pressure hydraulic gear pump including a
pump body supported by said housing and enclosing a substantially
flat inner rotor secured to said input shaft for rotation
therewith, and surrounded by a generally flat outer rotor, said
inner and outer rotors connected by intermeshing teeth, said outer
rotor having a rotor axis eccentric to said axis of said shaft,
said inner rotor having at least one less tooth than said outer
rotor, an annular wear plate disposed between said housing and said
pump body and engaging said inner and outer rotors, means defining
an arcuate oil receiving chamber within said wear plate adjacent
said teeth, means defining an inlet passage for directing oil
within said housing to said pump, means defining an outlet passage
for directing pressurized oil from said pump to said clutch
pressure chamber, electrically actuated valve means connected to
control the flow of oil through said outlet passage to said clutch
pressure chamber, and adjustable pressure relief valve means
connected to provide for adjusting the hydraulic pressure to said
clutch pressure chamber for conveniently selecting the torque
transmitted through said clutch plates and discs.
4. Apparatus as defined in claim 3 and including a ring member
within said pump body adjacent said wear plate and supporting said
outer rotor for rotation, said ring member having an inner
cylindrical surface with a centerline eccentric to said axis of
said shaft, and means supporting said ring member for limited
rotation in response to reversing the rotation of said shaft to
provide for producing high pressure fluid with said pump with
either direction of rotation of said shaft.
5. Apparatus comprising a housing having means for containing a
supply of oil, an input shaft and an output shaft rotatably
supported within said housing on a common axis of rotation, a
series of interfitting clutch plates and clutch discs within said
housing, said clutch plates mounted on said input shaft for
rotation therewith and the interfitting said clutch discs mounted
on said output shaft for rotation therewith, an annular piston
supported within said housing coaxial with said output shaft and
for non-rotating axial movement, said piston having an outwardly
projecting annular portion cooperating with said housing to define
a clutch pressure chamber, means connected to said piston for
applying an axially compressive force to said series of clutch
plates and discs in response to movement of said piston in one
axial direction to couple said input shaft with said output shaft,
means for recirculating oil within said housing and between said
plates and discs, a high pressure hydraulic gear pump including a
pump body removably attached to said housing and including a rotor
secured to said input shaft for rotation therewith, means defining
an inlet passage within the lower portions of said housing and said
pump body for directing oil within said housing to said pump, an
oil filter within said inlet passage, means on said pump body for
removing said oil filter, means defining an outlet passage for
directing pressurized oil from said pump to said clutch pressure
chamber, electrically actuated valve means connected to control the
flow of oil through said outlet passage to said clutch pressure
chamber, and adjustable pressure relief valve means connected to
provide for adjusting the hydraulic pressure to said clutch
pressure chamber for conveniently selecting the torque transmitted
through said clutch plates and discs.
Description
BACKGROUND OF THE INVENTION
In an oil shear clutch-brake unit of the general type disclosed in
U.S. Pat. Nos. 3,638,773 and 3,924,715, which issued to the
assignee of the present application, it is sometimes inconvenient
to provide a supply of pressurized air from a remote air compressor
to actuate the internal piston within the unit. It is also
sometimes difficult to obtain a source of clean dry pressurized air
for actuating the piston since it is not uncommon for moisture and
dirt to collect within the air lines of a manufacturing plant. If
the air supply contains moisture, the moisture can produce rust
within the clutch-brake unit, especially if no oil is introduced
into the air supply and the unit is not operated for an extended
period of time. If the air supply contains dirt particles, the
particles can prevent smooth operation of the piston and result in
excessive wear.
In the art of oil shear clutch and/or brake units with non-rotating
actuating pistons, it is known to operate the piston with hydraulic
fluid in place of air, especially if a hydraulic pressure line is
readily available, for example, from a remote hydraulic pump used
to drive hydraulic motors or actuators on the equipment where the
clutch and/or brake unit is being used. However, there are many
applications and uses for an oil shear clutch and/or brake unit
where the supply of clean dry air or hydraulic fluid is not
available and would involve significant additional costs to be made
available. In such installations, an electrically actuated clutch
and/or brake unit may be employed, but such a unit does not offer
the important advantages of an oil shear clutch and/or brake unit
as disclosed in the above mentioned patents.
SUMMARY OF THE INVENTION
The present invention is directed to an improved oil shear
clutch/brake unit or variable speed drive unit of the general type
as disclosed in the above-mentioned U.S. Patents and which provides
a self-contained system for operating the unit with only an
electrical power supply and without the need for a fluid supply
line such as a pneumatic line from an air compressor or a hydraulic
line from a remote hydraulic pump. Thus the apparatus of the
invention greatly simplifies the installation of an oil shear
clutch/brake unit or variable speed drive unit and eliminates the
possibility of any problem occurring due to an air supply line with
dirt and/or moisture. The apparatus of the invention also
eliminates the need for having a plumber install fluid lines to the
unit and assures rapid operation of the unit in response to
actuation of the electrical controls.
In accordance with one embodiment of the invention, a shaft extends
into one end portion of the housing of a clutch/brake unit and is
surrounded by a compact annular hydraulic pump system which
includes a pump housing forming an extension of the clutch/brake
housing. The annular pump housing encloses positive displacement
pumping elements including a set of inner and outer rotors formed
by flat gear-like members. The inner rotor is secured to the shaft
for common rotation and has external teeth which mesh with internal
teeth on the outer rotor located eccentrically to the shaft axis.
The outer rotor has one more tooth than the inner rotor and is
supported for rotation by a surrounding wear plate retained within
the pump housing.
Inlet and outlet passages are formed within the pump housing, and
the inlet passage receives a portion of the cooling oil collected
within the lower portion of the unit housing. The outlet passage
connects with passages within the unit housing for directing high
pressure hydraulic fluid to the non-rotating piston through a
manifold and a solenoid actuated control valve mounted on the
housing of the unit. The self-contained positive displacement pump
produces high pressure fluid in either direction of shaft rotation,
and pressure relief valves are provided to limit the maximum
hydraulic pressure and for selecting the pressures which operate
the clutch and brake according to the desired torque
transmission.
Other features and advantages of the invention will be apparent
from the following description, the accompanying drawings and the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an axial section of an oil shear clutch-brake unit
incorporating a self-contained hydraulic actuating pump in
accordance with the invention;
FIG. 2 is a view of the clutch-brake unit as taken generally on the
line 2--2 of FIG. 1;
FIG. 3 is a section taken generally on the line 3--3 of FIG. 1;
FIG. 4 is a fragmentary section taken generally on the line 4--4 of
FIG. 1; and
FIG. 5 is a diagrammatic illustration of the hydraulic control
system used on the clutch-brake unit shown in FIGS. 1-4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The clutch-brake unit shown in FIGS. 1 and 2, includes a cast metal
housing 10 formed by a first or input end portion 12, a second or
output end portion 14 and an intermediate portion 16 positioned
between the end portions 12 and 14. The end portions 12 and 14 and
the intermediate portion 16 are secured or clamped together by a
series of peripherally spaced and axially extending screws 17 (FIG.
2). The end portion 12 of the housing 10 has a set of counterbores
which receive a set of axially spaced antifriction ball bearings 19
and 21, and an input shaft 25 is rotatably supported by the
bearings in a manner similar to that shown in above-mentioned U.S.
Pat. No. 3,924,715. The input shaft 25 is adapted to be driven
continuously by some form of a prime mover such as an electric
motor.
The output end portion 14 of the housing 10 has a counterbore which
retains an antifriction ball bearing 33 for supporting an
intermediate portion of an output shaft 35. The output shaft 35 is
adapted to be connected to drive a machine which requires
intermittent starting and stopping. The inner end portion of the
output shaft 35 is supported by an antifriction ball bearing 36
which is retained within a counterbore formed within an enlarged
inner end portion 37 of the input shaft 25. An annular rotating
seal assembly 38 is retained by the output end portion 14 of the
housing 10, and the seal assembly 38 engages a low friction metal
sleeve on the output shaft 35 to form a fluid-tight seal for
retaining a supply of oil within the housing 10.
The intermediate portion 16 of the housing 10 projects inwardly and
forms an annular cylindrical chamber 39 positioned concentrically
with the output shaft 35. A non-rotating annular piston 40 includes
axially spaced rib portions 41 positioned within the chamber 39 for
axial sliding movement, and the piston is confined by a ring 42
retained within a counterbore in the housing portion 16. A set of
O-rings 43 are retained within corresponding grooves formed within
the intermediate housing portion 16 and the ring 42 and cooperate
with corresponding low friction plastic bands to form fluid-tight
seals with the adjacent corresponding cylindrical surfaces of the
piston 40.
Another set of O-rings 44 and a plastic band are retained within a
peripheral groove defined between the ribs 41 of the piston 40 and
form a fluid-tight seal with the cylindrical surface defining the
chamber 39. A set of circumferentially spaced passages 46 and 47
are formed within the intermediate housing portion 16 to provide
for selectively supplying a hydraulic fluid or oil (as will be
explained later) to the chamber 39 on opposite sides of the piston
ribs 41 so that the piston 40 may be selectively moved in opposite
axial directions within the housing 10.
The inner annular portion 37 of the input shaft 25 has a radial
thrust surface 52 and supports a series of peripherally spaced and
axially extending pins 53. A series of flat annular clutch plates
55 are suported by the pins 53 for rotation with the input shaft 25
and are interfitted between a series of clutch discs 58 splined to
the outer surface of the output shaft 25 for rotation with the
output shaft. An annular clutch member 60 is also splined to the
outer surface of the output shaft 35 for axial movement relative to
the output shaft and has a radial thrust surface 61 opposing the
surface 52 on the input shaft portion 37. The clutch member 60
receives the inner race of an antifriction support bearing 62 which
has an outer race confined within a counterbore formed within the
piston 40.
The output end portion 14 of the housing 10 supports a collar or
ring 63 which has a plurality of inwardly projecting pins 64 and is
secured by a set of peripherally spaced screws 67. The ring 63 has
an inwardly facing radial thrust surface 68 which opposes a radial
surface 69 of an inner annular portion of the piston 40. A series
of annular non-rotating brake plates 70 are positioned between the
opposing thrust surfaces 68 and 69 and are supported by the pins
64. The pins 64 extend into corresponding cavities within the
piston 40 to prevent rotation of the piston. The brake plates 70
interfit between a corresponding series of brake discs 78 which are
splined to the outer surface of the output shaft 35.
The output shaft 35 includes a set of integrally cast and
longitudinally spaced elongated impellers 80. Each impeller 80 has
a plurality of four axially extending arcuate passages 82 which are
peripherally spaced between arcuate ribs splined to the discs. The
passage 82 have corresponding arcuate inlets facing in the same
direction toward the end portion 14 of the housing. The passages 82
of one impeller 80 extend through the annular clutch discs 58, and
the passages 82 of the other impeller 80 extend through the brake
discs 78. The oil within the housing 10 is directed to the inlets
of the impellers 80 through a plurality of circumferentially spaced
passages 86 and 88 defined within the piston 40 and within the ring
63, respectively.
During operation of the clutch-brake unit, some of the oil which
collects within the input end portion 12 of the housing 10 flows to
the output end portion 14 through a set of lower corner passages
(not shown) located within the intermediate portion 16 of the
housing 10. A set of axially spaced inspection and oil fill ports
(FIG. 2) and removable plugs 94 are provided within the upper
portion of the housing 10 to provide for adding oil into the
housing 10 and for checking the static level of the oil which is
generallynear the axis of the shafts 25 and 35. The positive
outward flow of oil between the clutch plates and discs during
starting of the output shaft 35 and between the brake plates and
discs during stopping of the shaft 35, is highly desirable for
minimizing wear of the plates and discs and for cooling the plates
and discs.
In accordance with the present invention, the piston 40 is actuated
by hydraulic fluid supplied to the chamber 39 from a positive
displacement hydraulic pump 100. When high pressure hydraulic fluid
or oil is supplied through the passage 46, the oil pressure urges
the piston 40 towards the right (FIG. 1) to brake the output shaft
35 by compressing together the interfitting brake plates 70 and
brake disks 78. The piston 40 is normally urged toward the braking
position by a set of circumferentially spaced compression springs
103 mounted on corresponding pins 104 projecting axially from the
piston 40. The springs 103 engage an annular plate 106 which also
retains the outer race of the bearing 21. The lower portion of the
ring 106 supports an arcuate baffle member 108 which reduces
turbulance of the oil collected within the lower portion of the
housing 10.
As shown in FIGS. 1-3, the hydraulic pump 100 includes an annular
pump housing 110 and an annular steel wear plate 112 which mount on
the housing 10 and form an extension of the housing 10 around the
input shaft 25. The pump housing 110 has a cylindrical cavity 114
(FIG. 2) which receives a ring 116 having a cylindrical inner
surface 117 with a center axis 118 located eccentrically with
respect to the center axis 119 of the shafts 25 and 35. The ring
116 is free to rotate 180.degree., and the limits of clockwise and
counterclockwise rotation of the ring 116 are determined by a stop
pin 123 located within a semi-circular groove 124 formed within the
outer surface of the ring 116.
The pump 100 also includes an inner gear-like rotor 126 (FIG. 2)
which has fourteen peripherally spaced teeth 127. The inner rotor
126 is secured to the input shaft 25, and mating flat surfaces at
129 assure rotation of the inner rotor 126 with the input shaft 25.
Surrounding the inner rotor 126 is an outer rotor 134 which is free
to rotate within the cylindrical bore 117 of the ring 116. The
outer rotor 134 has fifteen circumferentially spaced inner teeth
136 or one more tooth than the inner rotor 126.
Hydraulic fluid or oil is supplied to the pump 100 through a
suction inlet passage 141 (FIG. 1) and a wire suction strainer 142
which projects into the lower portion of the housing 10. The
strainer 142 and a retaining spring 143 are removable for cleaning
of the strainer through a connecting chamber 144 which is normally
closed by an oval plate 146 secured to the housing 110 by a pair of
screws 147.
The inlet passage 141 connects with the space between gear teeth
127 and 136 and also with an arcuate cavity 153 (FIG. 3) within the
lower portion of the wear plate 112. A sealing ring 154 is retained
by the pump housing 110 and encloses an annular chamber 156 which
surrounds the input shaft 125 and is connected by small passage 157
to the inlet passage 141. The upper portion of the wear plate 112
has an arcuate cavity 161 (FIGS. 2 and 3) which connects with a
high pressure outlet passage 163 formed within the upper portion of
the pump housing. The passage 163 connects with an axially
extending passage 166 (FIGS. 1 and 3) which extends through the
wear plate 112 and into the housing 10. The inner end of the
passage 166 connects with a passage 168 within the annular plate
106, and a pressure relief valve 172, having a spring bias ball, is
located within the passage 168.
The inner rotor 126 and the outer rotor 134 of the pump 100 are
manufactured for positive displacement pump applications by the
Nichols Company of Portland, Me. and are sold under the trademark
of THE GEROTOR. The pump 100 is effective to produce a flow rate of
oil of approximately two gallons per minute at a shaft speed of
approximately 1800 R.P.M. The pressure relief 172 is selected to
provide a maximum hydraulic pressure within the passage 166, for
example, 250 p.s.i. Above this pressure, the valve 172 opens
sufficiently to allow oil to recirculate through the passage 168
and back into the housing 10 where the oil is collected in the
lower portion of the housing. The small quantity of oil which seeps
inwardly pass the inner rotor 126 returns to the suction inlet
passage 141 through the port 157.
A radial passage 178 (FIG. 1) is formed within the housing 10 and
connects with the pump outlet passage 166 to direct the high
pressure oil to a control valve system 180. The valve system 180
selectively controls the flow of high pressure oil to either the
passage 46 for actuating the brake or to the passage 47 of
actuating the clutch through correspondingly connecting passage 182
and 184 formed within the housing 10. The valve control system 180
includes a block-like manifold 186 (FIG. 4) which mounts on a
projection 187 of the housing section 12. The manifold supports a
two position, four way valve 188 which has a valve member 189
reciprocated or actuated by a solenoid 192. The solenoid actuated
valve 188 is commercially available.
A cylindrical chamber 194 (FIG. 4) is formed within the manifold
186 and connects with the passage 178 within the housing portion 12
so that the chamber 194 receives high pressure oil from the pump
100. A sintered bronze filter 196 is retained within the chamber
194 by a compression spring 197 and a threaded plug 198. The
filtered oil is directed through a passage 201 within the manifold
186 to the inlet port of the valve 188. One outlet port of the
valve 188 is connected by a passage 203 to a chamber 206 which has
an adjustable pressure relief valve 208. The passage 203 is also
connected to the passage 182 within the housing 10 and to the
passage 46 for moving the piston 40 in a direction to apply the
brake. Another passage 210 within the manifold 186 connects the
other outlet port of the valve 188 to another adjustable pressure
relief valve 212 and also to the passages 184 and 47 within the
housing 10. As shown in FIG. 5, oil return passages 214 and 216
connect the valve 188 and the valves 208 and 212 back to the oil
receiving chamber within the housing 10.
In operation of the clutch-brake unit described above, the input
shaft 25 is driven at a constant speed in a clockwise or a
counter-clockwise direction. The pump 100 produces a continuous
high pressure flow in either direction, for example, at two gallons
per minute. The pressure relief valve 172 within the pump outlet
passage 166 maintains a predetermined constant pressure within the
passages 166 and 178, for example, a pressure of 250 p.s.i. When
the oil pressure within the passage 166 exceeds this limit, the
valve 172 opens so that the oil is recirculated back into the
housing 10. When the solenoid 192 of the control valve system 180
is deenergized (FIG. 5), the pressurized oil from the pump 100
flows through the valve 188 to the passages 203, 182 and 46 to
pressurize the piston 40 and move it to the right (FIG. 1) to
compress the rotating brake discs 78 against the non-rotating brake
plates 70 for stopping the output shaft 35. The amount of braking
pressure applied by the piston 40 may be precisely selected by
adjusting the pressure relief valve 208. If the oil pressure
exceeds the selected pressure, the valve opens and permits oil to
return to the housing 10 through the passage 216.
When it is desired to release the brake and actuate the clutch of
the clutch-brake unit to couple the input shaft 25 to the output
shaft 35, the solenoid 192 is energized. The pressurized oil within
the passages 178 and 201 is directed through the passages 210, 184
and 47 for pressurizing the chamber 39 on the right side of the
piston ribs 41 and thereby shift the piston 40 to the left (FIG. 1)
against the springs 103 for clamping the interfitting clutch plates
55 and discs 58 together. The torque transmitted through the clutch
plates and discs may be precisely selected by adjusting the
pressure relief valve 212. When the pressure exceeds the selected
pressure, the valve 212 opens, and oil is returned to the housing
10 through the passage 216. As shown in FIG. 5, when one of the
passages 203 or 210 is pressurized, the other passage is connected
to the return passage 214 by the valve 188 so that the hydraulic
pressure within the chamber 39 on the opposite side of the piston
ribs 41 is released.
From the drawings and the above description, it is apparent that a
clutch-brake unit constructed in accordance with the invention,
provides desirable features and advantages. For example, as one
advantage, the unit may be installed and used in applications where
there is no source of pressurized air or pressurized hydraulic
fluid or where the pressurized air is not clean and dry. The unit
carries its own self-contained hydraulic pump which is compact and
provides a positive output pressure. The pump 100 also operates in
either direction of rotation of the input shaft 25 since the ring
116 rotates 180 degrees due to friction when the direction of
rotation of the rotors 126 and 134 is reversed. The pump also uses
the oil supply which is recirculated within the clutch-brake unit
for cooling and lubricating the clutch plates and discs and the
brake plates and discs. The hydraulic control system 180 further
provides for conveniently selecting the torque transmitted through
the clutch and through the brake and also cooperates with the
compact pump 100 to provide rapid response of movement of the
piston 40 and corresponding actuation of either the clutch or the
brake. It is also apparent that the pump 100 and a control system
similar to the system 180 may be used on an oil shear clutch only
unit or on a variable speed oil shear drive unit when a
self-contained actuating system is desired.
While the form of apparatus herein described constitutes a
preferred embodiment of the invention, it is to be understood that
the invention is not limited to this precise form of apparatus, and
that changes may be made therein without departing from the scope
and spirit of the invention as defined in the appended claim.
* * * * *